Benefits of Delayed Thrombectomy
There are no established benefits of deliberately delaying thrombectomy—in fact, every hour of delay reduces the likelihood of good functional outcomes, and treatment should be performed as rapidly as possible once thrombosis is detected. 1, 2
Time-Dependent Decline in Thrombectomy Effectiveness
The concept of "delayed" thrombectomy is fundamentally a misnomer in stroke care. The evidence consistently demonstrates that:
Each 1-hour delay to reperfusion reduces the odds of favorable disability outcomes (common OR 0.84; 95% CI 0.76-0.93), decreases functional independence by 5.2%, and results in a 6.7% absolute reduction in achieving lower disability scores. 2
Treatment benefit declines progressively with time: At 3 hours from symptom onset, the common OR for better outcomes is 2.79 (ARD 39.2%), declining to 1.98 at 6 hours (ARD 30.2%), and further to 1.57 at 8 hours (ARD 15.7%), with statistical significance lost after 7 hours and 18 minutes in unselected patients. 2
Extended Time Window Treatment (6-24 Hours): Not "Delayed" But "Selected"
What is sometimes misconstrued as "delayed thrombectomy" is actually highly selective treatment in extended time windows based on salvageable tissue identification:
Anterior Circulation Stroke (6-24 Hours)
Thrombectomy remains beneficial in carefully selected patients between 6-24 hours when clinical-imaging mismatch (DAWN criteria) or perfusion-core mismatch (DEFUSE-3 criteria) demonstrates salvageable brain tissue. 1, 3
The DAWN trial showed 49% vs 13% achieved good functional outcomes (mRS 0-2) with thrombectomy vs control (adjusted difference 33 percentage points; 95% CI 24-44), demonstrating that patient selection based on tissue viability, not arbitrary time delays, drives benefit. 3
This is not "delayed" thrombectomy—it is precision medicine identifying patients with slow infarct progression who retain salvageable tissue despite extended time from symptom onset. 1, 4
Basilar Artery Occlusion (Beyond 24 Hours)
For basilar artery occlusion specifically, thrombectomy may be reasonable beyond 24 hours on a case-by-case basis (Class IIb, Level C-EO), but outcomes are universally poor and there is tremendous uncertainty about benefit in these extreme time windows. 1
Successful recanalization was achieved in only 50% of patients treated beyond 24 hours, and this represents salvage therapy for patients with delayed diagnosis due to non-specific symptoms, not a deliberate delay strategy. 1
The Imperative Against Delay
Clinical Practice Mandates
Observation after IV alteplase to assess for clinical response before pursuing thrombectomy is contraindicated (Class III: Harm, Level B-R), as any delay worsens outcomes. 1
For dialysis access thrombosis, treatment should be performed rapidly following detection to minimize the need for temporary access, with no more than one femoral catheterization required. 1
Common Pitfalls to Avoid
Never delay thrombectomy for unnecessary testing—only blood glucose measurement must precede treatment in stroke patients. 4
Do not misinterpret extended time window trials as endorsing delay—these trials selected patients with favorable physiology (salvageable tissue), not those who simply presented late. 1, 3
Avoid the misconception that "waiting" improves outcomes—the only scenario where extended time windows show benefit is when imaging confirms viable penumbra, and even then, earlier treatment within that window is superior. 2
Context-Specific Considerations
When "Delayed" Treatment May Be Considered
The only legitimate scenarios for thrombectomy beyond standard time windows are:
Anterior circulation LVO with documented perfusion-core mismatch on CTP or DW-MRI between 6-24 hours from last known well. 1, 4
Basilar artery occlusion beyond 24 hours in highly selected cases where delayed diagnosis occurred, though outcomes remain poor and uncertain. 1
Witnessed late time window strokes (>6 hours) may have similar safety and efficacy to early treatment, but this reflects actual late presentation, not intentional delay. 5
In all cases, once the decision to treat is made, execution should be immediate—there is no benefit to further delay. 1, 2